Method for modification of maximum delivery limits in automatic drug delivery systems

Abstract

The disclosed embodiments are directed to methods for adjusting, on a per individual basis, the maximum delivery limit of insulin delivered to a diabetic person via an automatic insulin delivery system, particularly for a diabetic who receives basal or bolus doses of insulin via an automatic insulin delivery system. Various embodiments of the method disclosed herein may be incorporated into a dosing algorithm of an automatic insulin delivery system.

What is claimed is: 
     
         1 . A method comprising:
 executing a basal dosing algorithm, wherein each cycle of the algorithm comprises:
 receiving a blood glucose reading; 
 determining a required basal dose based on the received blood glucose reading; 
 adjusting a maximum delivery limit; and 
 determining a basal dose to be delivered, the basal dose comprising the lesser of the required basal dose and a dose limited by the maximum delivery limit. 
   
     
     
         2 . The method of  claim 1  further comprising:
 delivering the basal dose as one or more micro-boluses. 
 
     
     
         3 . The method of  claim 1  wherein the maximum delivery limit is constrained between a lower limit and an upper limit. 
     
     
         4 . The method of  claim 1  wherein adjusting the maximum delivery limit comprises:
 calculating a percentage of time during a past predetermined time period that delivery of insulin had been limited by the maximum delivery limit; and 
 adjusting the maximum delivery limit based on the calculated percentage. 
 
     
     
         5 . The method of  claim 4  wherein the adjusted maximum delivery limit is a product of a factor and a basal rate and further wherein the factor is a function of the calculated percentage and a current maximum delivery limit. 
     
     
         6 . The method of  claim 4  wherein the percentage of time during a past predetermined time period that delivery of insulin has been limited by the maximum delivery limit is calculated as a percentage of cycles of the basal dosing algorithm. 
     
     
         7 . The method of  claim 4  wherein a higher percentage indicates an upward adjustment of the maximum delivery limit and a lower percentage indicates a downward adjustment of the maximum delivery limit. 
     
     
         8 . The method of  claim 1  wherein adjusting the maximum delivery limit comprises:
 adding the received blood glucose reading to a set of blood glucose reading from a past predetermined time period; 
 calculating a standard deviation of the set of blood glucose readings; 
 adjusting the maximum delivery limit based on the calculated standard deviation. 
 
     
     
         9 . The method of  claim 8  wherein the adjusted maximum delivery limit is a product of a factor and a basal rate and further wherein the factor is a function of the calculated standard deviation and a current maximum delivery limit. 
     
     
         10 . The method of  claim 8  wherein the standard deviation of the set of blood glucose readings is calculated every cycle of the basal dosing algorithm. 
     
     
         11 . The method of  claim 8  wherein a wider standard deviation indicates an upward adjustment of the maximum delivery limit and a narrower standard deviation indicates a downward adjustment of the maximum delivery limit. 
     
     
         12 . The method of  claim 1  wherein adjusting the maximum delivery limit comprises:
 calculating a percentage of time during a past predetermined time period that a blood glucose reading has indicated hypoglycemia; and 
 adjusting the maximum delivery limit based on the calculated percentage. 
 
     
     
         13 . The method of  claim 12  wherein the adjusted maximum delivery limit is a product of a factor and a basal rate and further wherein the factor is a function of the calculated percentage and a current maximum delivery limit. 
     
     
         14 . The method of  claim 12  wherein the percentage of time during a past predetermined time period that a blood glucose reading has indicated hypoglycemia is calculated as a percentage of cycles of the basal dosing algorithm. 
     
     
         15 . The method of  claim 12  wherein a higher percentage indicates a downward adjustment of the maximum delivery limit and a lower percentage indicates an upward adjustment of the maximum delivery limit. 
     
     
         16 . A method for determining a nighttime maximum delivery limit for use during a nighttime period comprising:
 applying a nighttime maximum delivery limit during a nighttime period; and   applying a daytime maximum delivery limit during a non-nighttime period.   
     
     
         17 . The method of  claim 16 , further comprising:
 determining that a blood glucose reading below a low threshold has been received during one or more nighttime periods of a predetermined number of past nighttime periods;   determining that the number of blood glucose readings below a low threshold satisfy one or more triggering conditions for triggering the calculation of a new nighttime maximum delivery limit; and   adjusting the nighttime maximum delivery limit.   
     
     
         18 . The method of  claim 17  wherein a first triggering condition comprises receiving a blood glucose reading below a low threshold on two consecutive nights. 
     
     
         19 . The method of  claim 18  wherein a second triggering condition comprises receiving a blood glucose reading below a low threshold on three nights of the past seven nights. 
     
     
         20 . The method of  claim 17  wherein the nighttime maximum delivery limit comprises a product of a basal rate and a factor, the factor being the lesser of a current factor or a factor calculated as the mean of factors calculated on a predetermined number of past nights wherein no blood close glucose reading below the low threshold has been received.